プロペラファンの騒音低減化に関する実験的研究 : 第2報, 騒音特性

概要

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The effects of various parameters of a propeller fan, such as the axial position of the fan rotor relative to the duct inlet, the duct width, the inlet shape and the tip clearance on the fan noise, have been investigated systematically in order to make clear the optimum conditions for a low-noise fan. In this research the noise characteristics are investigated in relation to the aerodynamic characteristics discussed in the previous paper. It has been clarified that there is a close relation between noise and aerodynamic characteristics, that is, the higher the peak efficiency, the lower the specific sound noise K_<SL> if the noise level is rated by the L level of a sound level meter. If it is defined by A level, however, the specific sound level K_<SA> does not show the same relations that K_<SL> has with the parameters tested. This is due to the difference in the spectrum distribution of the noise.
1990-11-25